Navigation technology keeps developing with development of car networking and mobile communications, and with an increasingly higher requirement on city management. Early route planning is based mostly on a static Geographic Information System (GIS) map, computing a route by dynamic planning or the like, and thus is highly dependent on the map. A process of mapping, cartography, and map releasing often may set some time, such that map information always lags behind an actual situation. In addition, many emergencies may impact actual road traffic, thereby affecting accuracy and effectiveness of a navigated route. A trend to combine a GIS map and actual road condition data has gradually developed in navigation technology.
There are two main sources of existing road condition data, namely road condition data from free Traffic Message Channel (TMC) and commercial road condition data. The road condition data from the TMC are released by a traffic management department, with real-time data mainly coming from tollgate monitoring and police deployment, leading to good real-time performance. However, a TMC system may not be deployed in every region, leading to limited coverage and limited amount of information. The commercial road condition data mainly come from Float Car Data (FCD), with road condition information being collected generally using an on-cab device deployed by a cab company. Constrained by commercial, technical, and historical factors, the commercial road condition data can provide but road condition information on only a few cities, often with a large delay and poor real-time performance.
To sum up, with existing navigation technology, road condition data cover but a small area, with poor real-time performance, failing to meet a stringent navigation demand. With route planning based solely on a GIS map, it is difficult to guarantee the accuracy and effectiveness of a computed navigated route in case of incorrect or outdated map information, often leading to a large deviation from an expected navigation outcome or even giving a wrong route.